From mboxrd@z Thu Jan 1 00:00:00 1970 From: Li Zefan Subject: Re: cgroup_fj tests will stick the nort kernel Date: Thu, 25 Apr 2013 16:44:30 +0800 Message-ID: <5178ECEE.4070907@huawei.com> References: <5170F28F.3060002@huawei.com> <51750563.8050301@huawei.com> <1366646447.9609.131.camel@gandalf.local.home> <5176217E.8030008@huawei.com> <5178C922.3060506@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Steven Rostedt , Thomas Gleixner , linux-rt-users , zhangwei To: Qiang Huang Return-path: Received: from szxga01-in.huawei.com ([119.145.14.64]:51749 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755851Ab3DYIpQ (ORCPT ); Thu, 25 Apr 2013 04:45:16 -0400 In-Reply-To: <5178C922.3060506@huawei.com> Sender: linux-rt-users-owner@vger.kernel.org List-ID: > And the patch below, I added your signed-off-by if it looks good to you. Don't... > Here is the patch seems solve the problem, it looks all good in my box, my > only concern is how will this affect our RT code. > > >>>From 8e4fa4e9a7b510bdaf90b8140ce1e847375abccf Mon Sep 17 00:00:00 2001 > From: Qiang Huang > Date: Thu, 25 Apr 2013 10:22:01 +0800 > Subject: [PATCH] sched: don't clear PF_THREAD_BOUND in select_fallback_rq > > This is revert of "sched-clear-pf-thread-bound-on-fallback-rq.patch" > (commit 0d939066acdcb in v3.4-rt),. > > Select_fallback_rq() can be easilly called during system boot, because > select_task_rq_fair() just return task_cpu(p) for bounded kernel threads, > which is 0 during system boot and not in tsk_cpus_allowed, so > select_fallback_rq() is called and PF_THREAD_BOUND is cleared. In my > box, 1/3 bounded kernel threads will clear that flag after boot. > > And it will cause problems, for example: > # for pid in `ps -e -o pid`; do taskset -p -c 0-15 $pid; done > this command will cause system hung. > > What's more, I don't see why we need to clear this flag any more, > because "cpu/rt: Rework cpu down for PREEMPT_RT" already remove the > optimization for PF_THREAD_BOUND on migrate_disable/enable. > > Signed-off-by: Qiang Huang > Signed-off-by: Li Zefan You shoudn't have added my SOB... I didn't write this patch and I didn't even sugguest this fix or check if this is a correct fix. Please read Documentation/SubmittingPatches to learn how SOB should be used. > --- > kernel/sched/core.c | 6 ------ > 1 files changed, 0 insertions(+), 6 deletions(-) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 751ec60..8db6e3b 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -1327,12 +1327,6 @@ out: > } > } > > - /* > - * Clear PF_THREAD_BOUND, otherwise we wreckage > - * migrate_disable/enable. See optimization for > - * PF_THREAD_BOUND tasks there. > - */ > - p->flags &= ~PF_THREAD_BOUND; > return dest_cpu; > } >